Clarifying the Caffeine Controversy - Page 2

Running the Risks

Bumping your doses to 500 milligrams and higher, you run the risk of more serious side effects, which may include nausea, heart palpitations, diarrhea and tremors. Because electrolytes play an important role in regulating cardiac rhythm, combining caffeine with electrolyte disturbances—very common in the later stages of an ultramarathon—may prime a runner’s heart for trouble.

Antony Chu, M.D., Director of complex Ablation in Arrhythmia Services at the Rhode Island and Miriam hospitals, warns, “Within the trail-runner’s world, the effects of electrolyte abnormalities that can exist under conditions of extreme physiologic stress and concomitant high-caffeine ingestion are unknown.”

Caffeine may also exacerbate heat intolerance by acting as a diuretic. Because caffeine is a stimulant, it boosts perspiration and metabolic rate, speeding fluid losses during intense exercise and leading to dehydration.

Life or Death

Further studies are underway, and more definitive information relating to caffeine use with exercise should be available by June 2013, following a summer consortium of medical professionals held in Spain.